ST. LOUIS, July 5 -- Sen. Barack Obama ended a week's focus on values by giving a conference of the African Methodist Episcopal Church a highly personal account of his spiritual journey and a promise that he will make "faith-based" social service "a moral center of my administration."

The address, to one of the oldest and largest African American denominations, brought the senator from Illinois back to friendlier ground after a week's tour through Appalachian Ohio, conservative Missouri, the conservative stronghold of Colorado Springs, North Dakota and hardscrabble Montana. But in its religious tones, the address had a far wider intended audience.

"In my own life, " he said, "it's been a journey that began decades ago on the South Side of Chicago, when, working as a community organizer, helping to build struggling neighborhoods, I let Jesus Christ into my life. I learned that my sins could be redeemed and that if I placed my trust in Christ, that he could set me on the path to eternal life when I submitted myself to his will and I dedicated myself to discovering his truth and carrying out his works."

He suggested that he would apply the lessons of his faith to the problems he would face if he became president. "The challenges we face today -- war and poverty, joblessness and homelessness, violent streets and crumbling schools -- are not simply technical problems in search of a 10-point plan," he said. "They are moral problems, rooted in both societal indifference and individual callousness, in the imperfections of man. And so the values we believe in -- empathy and justice and responsibility to ourselves and our neighbors -- these cannot only be expressed in our churches and our synagogues, but in our policies and in our laws."

Of the two presumptive nominees for president, Obama has been far more outspoken about his religious beliefs than Sen. John McCain. Evangelical Christian leaders have remained skeptical, however, that Obama's faith comports with their own, especially given his support for gay and abortion rights.

James Dobson, the influential leader of Focus on the Family, last month accused Obama of "deliberately distorting the traditional understanding of the Bible to fit his own world view, his own confused theology." Last week, some Christian conservatives sharply criticized Obama for unveiling a new campaign symbol for outreach to gay voters and for opposing efforts in California to pass a state constitutional amendment undoing a court ruling that legalized same-sex marriage.

But Obama said Saturday that he is optimistic about his ability to win support among evangelical Christians -- if not to win a majority of their votes, then at least to hold down McCain's margins. McCain has had his share of problems with the group since, after his losing 2000 campaign, he described some evangelical Christian leaders as agents of intolerance. Dobson, for instance, continues to say he will never vote for the Republican.

"If we show up," Obama told reporters aboard his campaign plane as he left Montana on Saturday, "if we let folks know that we're interested in them and we share a lot of common values, then we're not going to win 100 percent of the evangelical vote. We might not even win 50 percent of the evangelical vote. But we will at least take some of the sharp edges off this divide that's existed in our politics. And that hopefully will allow people to listen to each other, and that will help me govern over the long term."

Last month, Obama met for an extended session in Chicago with Franklin Graham, Billy Graham's son and the leader of the Graham ministry, along with about 30 other evangelical Christian leaders. McCain sought out an audience with Franklin and Billy Graham last week at the family's mountaintop retreat in western North Carolina.

On Monday and Tuesday, Obama will be back in Republican territory, campaigning in North Carolina and Georgia, where Christian conservatives remain a powerful force.

"Democrats can't shrink the map to win. I think we have to expand the map to win," he said. "And for a bunch of election cycles, we had such a narrow path to victory that if one thing went wrong, we were going to lose. I can't guarantee that we are going to win in any Southern state anymore than I can guarantee we're going to win in a place like Montana or North Dakota, but I can guarantee that we can give it a good shot."

Last week, Obama expressly came out against using "mental distress" as a justification for late-term abortions, a position widely seen as the latest in a string of moves toward the political center but one aimed specifically at Christian conservatives.

"Historically, I have been a strong believer in a woman's right to choose, with her doctor, her pastor, her family," he said Saturday. "And I've been consistent in saying you have to have a health exception on any significant restrictions or bans on abortions, including late-term abortions.

"It can be defined by physical health. It can be defined by serious clinical mental health diseases," he continued. But "it's not just a matter of feeling blue."

Such statements may run the risk of alienating Obama's liberal activist supporters. And Republicans have tried to counter all of Obama's moves to the center, framing them as proof that he is a typical politician without an ideological core, not the new breed of politician he says he is. The Republican National Committee accused him Saturday of flip-flopping on long-held beliefs regarding abortion.

But such moves could also broaden his appeal in battleground states and in Republican regions trending Democratic.

In his speech here, he tried to dispel the notion that he comes from Muslim roots, pointedly mentioning that his father, a Kenyan who left his family and returned to Africa when Obama was a small child, was an atheist.

Obama acknowledged how hard it has been for the campaign to dispel false rumors that he is Muslim or that he is not an American, as well as a sense among some voters that he lacks patriotism.

"In fairness to the American people, I am relatively new on the political scene, compared to a John McCain or a Hillary Clinton. My profile is not typical of a presidential nominee, not only because I'm African American, but I'm relatively young as a candidate," he said. "So it's not surprising that people are still getting to be familiar with what I've done, who I am, what I stand for. I do think it's been fed pretty systematically by e-mails that have been sent out. There's a concerted strategy to raise questions about me and to spread lies about my background, and in the Internet age, that's pretty effective.

"What's remarkable is that despite all that, things that have been going on since we announced -- I'm the nominee and have a pretty good shot at winning," he added.